1. Field of the Invention
The invention relates to a holding mechanism for holding integrated circuit cards, preferably as a Subscriber Identity Module (SIM) for a cellular phone. A SIM card is a module, which unambiguously identifies a telephone subscriber. The contact layout of such a module corresponds to the contact layout of an IC card in accordance with ISO 7816 standard; however, the outer dimensions of the SIM card are significantly smaller, i.e. they are 25xc3x9715 mm, compared with 85.5xc3x9754 mm for the IC card.
2. Description of Prior Developments
The use of this kind of holders is well known because all GSM phones have to be equipped with a SIM card terminal.
U.S. 5.920.552 describes such a SIM card terminal having a base part with a terminal having contact elements facing towards the integrated circuit card when inserted, and a pivotal lid that keeps the card in position when the lid is in the closed position. In closed position the lid may slide along the card in order to engage locking tabs for locking the position of the lid. Even though this concept has proven its quality in practice the overall size of the unit is substantial greater than the SIM card it self. When the phones are continually reduced in size it is desired to get rid of such a big component to be placed on the Printed Circuit Board (PCB) of the phone.
An object of the invention is to provide a compact holding mechanism for an integrated circuit card.
This purpose is obtained by a holding mechanism for an integrated circuit card comprising a housing part having a recess for receiving the integrated circuit card, a terminal unit provided in said depression having contact elements facing towards the integrated circuit card when inserted. The recess is formed with guiding means for maintaining the position of the integrated circuit card relative to said contact elements of the terminal unit. A pivotal lid has means for being mounted onto the lid of the housing part for covering the recess in a closed position. Locking means is provided for engaging the lid in order maintain the lid in a releasable locked position upon this engagement. The lid has with biasing means for biasing the integrated circuit card towards the contact elements of the terminal unit when the lid is in the locked position.
Hereby the biasing means of the lid ensures a sufficient contact between the resilient contact elements of the terminal unit and the contact pads of the integrated circuit card even though the tolerances of the overall holding mechanism has become less restrictive. This means that a single unit no longer will be needed. Therefor it will be possible to obtain a holding mechanism being significantly better integrated with the remaining part of the phone.
The existing SIM terminal units based on U.S. 5.320.552 have a footprint on the Printed Circuit Board corresponding to approximately 17xc3x9730 mm while the holder mechanism according to the invention only has to include the contact elements in the base part mounted in the Printed Circuit Board. Therefore the footprint of the holder mechanism can be reduced to 9xc3x9712 mm or even smaller. The base part of the holder mechanism is a standard component and height of this component is approximately 1 mm. The bottom of the recess in the wall part is aligned with the top surface of the base part and therefore a free space will be available below the integrated circuit card and in between the Printed Circuit Board and the wall part. The height of this space will be 0.5-0.8 mm and the space can be used on thin SMD components or insulation for separating the metallic wall part from the printed circuit.
The lid of the holding mechanism is attached to the wall part and provided as a curved structure and thereby being elastically deformable. Preferably the part of the lid opposite to the mounting means is more resilient than the remaining part of the lid. Preferably the material used for the lid is Polyacrylamid.